ICOS, known as a marker of T cell activation,30 is an essential costimulatory molecule for T cell enhancement.31, 32 Yi et al. have reported that T cells from peripheral blood and tumor tissues of patients treated with anti‐CTLA‐4 for NSCLC had an increased expression of ICOS.33 ICOS upregulation on T cells is correlated with increased clinical responses induced by CTLA‐4 inhibition.34, 35 Therefore, ICOS agonist mAbs could enhance the effect of inhibitory checkpoint inhibitors. This evidence concerns the gene CTLA4 and non-small cell lung carcinoma.